44 RESPONSE IN THE LIVING AND NON-LIVING 



CHAPTEE VI 



PLANT RESPONSE ON DIPHASIC VARIATION 



Diphasic variation Positive after-effect and positive response 

 Radial E.M. variation. 



WHEN a plant is stimulated at any point, a mole- 

 cular disturbance the excitatory wave is propagated 

 outwards from the point of its initiation. 



Diphasic variation. This wave of molecular dis- 

 turbance is attended by a wave of electrical disturb- 

 ance. (Usually speaking, the electrical relation between 

 disturbed and less disturbed is that of copper to zinc.) 

 It takes some time for a disturbance to travel from 

 one point to another, and its intensity may undergo 

 a diminution as it recedes further from its point of 

 origin. Suppose a disturbance originated at C ; if two 

 points are taken near each other, as A and B, the 

 disturbance will reach them almost at the same time, 

 and with the same intensity. The electric disturbance 

 will be the same in both. The effect produced at A 

 and B will balance each other and there will be no 

 resultant current. 



By killing or otherwise reducing the sensibility of B 

 as is done in the method of injury, there is no response 

 at B, and we obtain the unbalanced response, due to 

 disturbance at A ; the same effect is obtained by putting 



